For example, JP2009-036108A discloses an exhaust gas recirculation (EGR) apparatus as a valve apparatus that has an electric actuator, which drives a valve and is controlled by a control device.
In the EGR apparatus of JP2009-036108A, an electric motor of the electric actuator is feedback controlled with the control device such that a sensed opening degree (an actual opening degree), which is sensed with an opening degree sensor, coincides with a target opening degree of the valve, which is set according to a target EGR ratio.
The measures, which reduce a time required for fully closing the valve at the time of fully closing the valve in the valve open state, may include an energization control operation of the electric motor in the valve closing direction. At the time of executing the energization control operation, when the mechanical stopper makes strong abutment (collision) at a full closing degree θ0 of the valve, a collision sound may be generated, and/or damage may occur due to the collision.
In order to avoid the mechanical collision of the mechanical stopper, the valve closing speed of the valve needs to be reduced immediately before the full closing degree θ0.
As shown in FIG. 4A, the measures, which avoid the mechanical collision of the mechanical stopper, may include (i) controlling energization of the electric motor in the valve closing direction until reaching of the sensed opening degree to an energization stop opening degree θa, which is set on a valve opening side of the full closing degree θ0, and (ii) stopping the energization of the electric motor after reaching of the sensed opening degree to the energization stop opening degree θa, and returning the valve to the full closing degree θ0 only by the urging force of the return spring.
However, in the case where the energization stop opening degree θa is set as the target opening degree θb, which is set for the time of fully closing the valve, when the valve opening degree approaches the energization stop opening degree θa, the closing speed of the valve is reduced by the feedback control, as shown in FIG. 4B. Specifically, the closing speed of the valve is largely reduced immediately before the energization stop opening degree θa, so that the speed reducing time is required before the time of reaching to the energization stop opening degree θa.
Furthermore, after the stopping of the energization of the electric motor, the valve, the speed of which is sufficiently reduced, is closed only by the urging force of the return spring that has the reduced restoring force. Therefore, the time, which is from the energization stop opening degree θa to the full closing degree θ0, is lengthened.
Even when the energization control of the electric motor in the valve closing direction is made to reduce the time required for fully closing the valve, the closing speed of the valve is reduced immediately before the energization stop opening degree θa by the feedback control, and the valve, the speed of which is sufficiently reduced, is fully closed only by the urging force of the return spring. Therefore, the response of the valve at the time of fully closing the valve is deteriorated.